The present invention relates to a gas insulated switchgear suited to a dismantling operation of a unit. A gas insulated switchgear is superior in size reduction, insulation performance, and safety and widely used in electric plants such as substations. A gas insulated switchgear includes a combination of a plurality of components such as a breaker, disconnecting switches, grounding switches, a potential transformer, and others and a power supply conductor for electrically connecting these devices to each other in a closed enclosure charged with insulating gas. For example, the gas insulating switchgear described in Japanese Patent Application Laid-Open 10-75513 includes a combination of line side units having a bus unit having a bus conductor, breaker unit having a breaker, arrester, potential transformer, and others.
The aforementioned units are connected via insulating spacers so as to keep air-tightness between the units. For that purpose, a flange is formed in each unit so as to connect each insulating spacer. For example, in the gas insulating switchgear described in Japanese Patent Application Laid-Open 10-75513, the flange in each unit is formed as an outer flange and when dismantling the units, in the state that the insulating spacer is attached to the flange of one unit, the other unit is separated. In addition to this gas insulating switchgear in which the flange of each unit is formed as an outer flange, there are ones described in Japanese Utility Model Application Laid-Open 62-98420 and Japanese Utility Model Application Laid-Open 63-74011. Particularly in the gas insulating switchgears described in Japanese Patent Application Laid-Open 64-77411 and Japanese Utility Model Application Laid-Open 59-183129, the flange of one unit is formed as an outer flange and the flange of the other unit is formed as an inner flange.
In a conventional gas insulating switchgear in which the flange of each unit is formed as an outer flange, the mechanical strength is relatively weak and there are many parts to be used. In a conventional gas insulating switchgear in which the flange of one unit is formed as an outer flange and the flange of the other unit is formed as an inner flange, when dismantling the units, the insulating spacer can be attached only to either one of the outer or inner flanges.
The present invention is planned in view of the above situations and an object thereof is to provide a gas insulated switchgear for dismantling units in the state that an insulating spacer can be attached to the both flanges of the units even if an inner flange is used. Another object of the present invention is to improve the dismantling operability of a gas insulated switchgear in which the flange of one unit is formed as an outer flange and the flange of the other unit is formed as an inner flange.
The gas insulated switchgear of the first present invention includes a unit having an inner flange, a unit having an outer flange, and insulating spacers existing between the flanges of the units, wherein a closed-end tapped hole is formed in the inner flange, and an idle hole is formed in the outer flange, and a tapped hole with a larger diameter than that of the hole in the inner flange is formed in each insulating spacer.
The gas insulated switchgear of the second present invention includes a unit having an inner flange, a unit having an outer flange, and insulating spacers existing between the flanges of the units, wherein when separating the inner flange side in the state that the insulating spacer is attached to the outer flange side, a bolt is screwed into a tapped hole made in the insulating spacer so as to connect the outer flange to the insulating spacer and when separating the outer flange side in the state that the insulating spacer is attached to the inner flange side, a bolt is screwed into a tapped hole made in the inner flange so as to connect the inner flange to the insulating spacer.
The gas insulated switchgear of the third present invention includes a unit having an inner flange, a unit having an outer flange, and insulating spacers existing between the flanges of the units, wherein a plurality of first holes with a diameter of D1 are formed in the periphery of the outer flange, and a plurality of second holes with a diameter of D2 are formed in the periphery of each insulating spacer, and a plurality of third holes with a diameter of D3 are formed in the periphery of the inner flange, and the relationship between the diameters of the holes is set to D1xe2x89xa7D2xe2x89xa7D3.
In the gas insulated switchgear of the present invention, in the state that the insulating spacer is attached to the flange of one unit, the other unit can be separated or in the state that the insulating spacer is attached to the flange of the other unit, one unit can be separated, so that the maintenance and inspection operation or the trouble recovery operation can be performed for a unit not to be maintained and inspected or a unit free from a trouble unless it is exposed to the air. As a result, the space for gas collection, evacuation, and gas charging can be made smaller, so that the unit dismantling time can be shortened. Furthermore, the space that there is a possibility of mixing of foreign substances causing dielectric breakdown can be made smaller, so that the reliability of the gas insulated switchgear can be improved.
In the connection structure that insulating spacers exist between outer flanges of two units, a large space is required, and moreover the mechanical strength is relatively weak, and it takes a lot of time to attach and remove stud bolts, and there are many parts used. However, in the gas insulated switchgear of the present invention, the outer diameter can be made smaller and the mechanical strength can be ensured. Furthermore, there is no need to use stud bolts, and as a result, the operability can be improved and the number of parts can be reduced.